Abstract

Pseudomyxoma Extra Peritonei (PE) is a rare finding, the most common cause is the rupture of a mucocele of the appendix into the retroperitoneum. Here we report a case of a 52 years old female
patient with a mass in the right abdomen and vague lower abdominal pain underwent resection
of an extraperitoneal encapsulated mass. The histopathological examination revealed a mucinous
pseudomyxoma with a low grade of differentiation. We report a case of pseudomyxoma extra
peritonei with a review of literature.

Case Presentation

A 52-year-old female patient was referred to our hospital for a mass in the right abdomen and
vague lower abdominal pain. The only remarkable event in her past history was a right breast fibroid
neoplasm that had been removed 10 years before.Investigations
An abdominal examination revealed a large, fixed mass in the subcostal right region. There were
no cervical, axillary or inguinal lymphadenopathies, nor any signs of ascites. Other tests were normal
with the exception of a slight increase in the CEA level (8.5 ng/ml; normal value: 0-2.5). Computed
tomography (CT) of the chest and abdomen revealed a roundish, 100 mm x 70 mm x 80 mm mass in
the right flank, with regular margins, a partial capsule and a19-mm internal calcification with mural
calcification and hyperdense central striae (Figure 1). The US-guided aspiration of the mass yielded a cellular material. The upper and lower endoscopic examinations were negative.Treatment
The case was discussed ata multidisciplinary team meeting. As it proved difficult to make
a preoperative diagnosis, the patient underwent surgery, during which an extraperitoneal
encapsulated mass that was free of all surrounding structures, including the pancreas, kidneys
and bowel, was found. This mass was resected completely without breaking the capsule. The
histopathological analysis revealed a mucinous pseudomyxoma with a low grade of differentiation.
Immunohistochemistry was positive for CK20 and CK7. The patient was discharged 4 days after
surgery without any complications. At follow-up, 3 years later, there was no sign of recurrence.

Figure 1

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Figure 1
CT scan of the abdomen and pelvis, demonstrating the mass in the right abdomen.

Table 1: 37 reported cases appendix.

Table 1
37 reported cases appendix.

Figure 2

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Figure 2
Surgical specimen.

Discussion

Werth [1] first described pseudomyxoma peritonei in 1884 as the presence of mucinous and gelatinous material in the peritoneal cavity. In 1948, Bonann [2] reported a pseudomyxoma involving the retroperitoneum alone, which was subsequently displayedby Coppini [3] in 1950. Twenty years later, Early [4] described a retroperitoneal mucocele of the appendix that contained 10 litres of mucus that had not ruptured, thus allowing
a complete curative excision to be performed; this was referred to by
Moran [5] as pseudomyxoma extra peritonei (PE) in 1988. Shelton et
al. [6] later named it Pseudomyxoma retroperitonei. Pseudomyxoma
retroperitoneal is a rare disease of which there are only 37 reported
cases in the literature; the most common cause is the rupture of a
mucocele of the appendix into the retroperitoneum (Table 1). It
affects both sexes to the same extent, prevalently after the age of 60
years [7], with other potential primary sites including a mucinous
neoplasm of the ovary or bowel, or a primary retroperitoneal
mucinous cystadenoma/cystadenocarcinoma; a histopathological
analysis reveals aggregates of mucus and epithelial cells displaying
varying degrees of atypia and differentiation. The cells are generally
positive for CK20 and negative for CK7 [8]. Pseudomyxoma
can be classified as grade I or benign disseminated peritoneal
adenomucinosis, as grade II or intermediate subtype, and as grade
III or malignant peritoneal mucinous carcinomatosis [9,10]. In the
majority of cases the pathogenesis of Pseudomyxoma retroperitonei
is explained by a leak through the peritoneum (retroperitoneal
presentation associated with intraperitoneal pseudomyxoma). In the
absence of peritoneal pseudomyxoma, a variant of the anatomy of the
appendix (retroperitoneal location) may explain the extraperitoneal
pseudomyxoma, though this hypothesis is still speculative [11].
A preoperative diagnosis is very rare; symptoms such as fatigue,
decreased appetite with weight loss, the presence of a palpable mass
and slowly progressing abdominal or lumbar pain are common. CEA
and CA 19.9 are reported to be increased in 56% - 75% and 58% - 67%
of patients, respectively [10]. Ultrasound may detect the mucina as
retroperitoneal fluid and help to make a diagnosis by means of needle
aspiration, while CT with intravenous, oral and rectal contrast may
distinguish the mucinous substance from the normal watery fluid
by means of density property analysis (5-20 Hounsfield units for
mucous vs 0 Hounsfield units for water) [9]. At CT, Pseudomyxoma
retroperitonei appears as a mass that is often multicystic, has septa
or thick walls and may be characterized by mural calcifications that
displace adjacent structures [12]. Surgery
The treatment of pseudomyxoma differs substantially depending
on whether it is intraperitoneal or extraperitoneal. For intraperitoneal
pseudomyxoma, Sugarbaker et al. [13] recommended an aggressive,
complex surgical procedure that involves extirpation of the mucinous
material, debulking and peritonectomy in order to remove as much
macroscopic disease as possible (cytoreductive surgery, CRS) using
heated intraperitoneal hyperthermic chemotherapy (HIPEC).
By contrast, the recommended treatment for extraperitoneal
pseudomyxoma is, as for benign disease, resection of the site of origin
sometimes followed by systematic chemotherapy [7]. Glehen et al.
[14] reported a median survival of 156 months, with 5- and 10-year
survival rates of 72% and 55%, respectively, in 501 pseudomyxoma
peritonei patients who had undergone CRS (complete or incomplete)
followed by HIPEC. The majority of the patients (~70%) underwent
complete cytoreduction. This uniform treatment approach has led
to a better 10-year survival than that recorded in historical controls
[15,16]. Although no data are available on the use of hyperthermic
retroperitoneal chemotherapy, this treatment should be considered
owing to the high recurrence rate [7]. Surgery
The risk of recurrence is such that follow-up, based on a physical
examination, CT scan and serum markers, is essential. Combined
treatment in Pseudomyxoma retroperitonei is associated with a 20-
year survival rate in up to 70% of patients [17], whereas the survival
rate for pseudomyxoma intra-peritonei, in which vital abdominal
structures are involved, is shorter [5].